When an action potential is initiated these ion channels go from their closed state to their open state, when they open sodium can now pass through.

当动作电位形成时,离子通道,从关闭状态转到打开状态,当通道打开时,钠离子就可以通过

耶鲁公开课 - 生物医学工程探索课程节选

And that's all that's big enough to pass through or small enough to pass through. And if we go up even just one row on the periodic table to potassium, what we actually see is now that it's going to be too large, and, in fact, a potassium solvated with one water molecule won't go through our channel.

就是这样刚好大到它通过,或者说刚好小到它通过,即使我们再沿着周期表往下走仅仅一行到钾离子，我们看到的就将是它的个头太大了，实际上，溶解于一个水分子的单个钾离子,不能穿过我们的通道。

麻省理工公开课 - 化学原理课程节选

In order for it to get inside the cells and go through them there have to be transporters which specifically allow glucose to pass into the cell and then out into our body.

为使其能进入并穿过细胞,肠上皮必须具有葡萄糖特异性的转运蛋白,使葡萄糖能够穿过细胞进入体内

耶鲁公开课 - 生物医学工程探索课程节选

You've got to spend the time to make sure that everything is well defined before you start trying to work out these problem More about the path. There are a couple ways you could go through that pass If I look at this smooth path here.

你要花时间确认,在你开始尝试解题前,切已经被很好地定义,关于路径还有些问题,你可以用两种不同的方式经过这条路径,看这条平滑的路径。

麻省理工公开课 - 热力学与动力学课程节选

Now, sodium and potassium don't ordinarily move across membranes, they're charged molecules, they can't dissolve, they can't permeate through a cell membrane, but they go through because there are channels that allow them to pass through in the membrane.

钠和钾通常是不能跨过细胞膜的,它们都是带电粒子,它们不能溶解在细胞膜中,不能渗透通过细胞膜,但它们之所以能通过细胞膜,全赖膜上离子通道的作用

耶鲁公开课 - 生物医学工程探索课程节选